Study Assesses Incidence of ADHD

Health officials estimate the prevalence is anywhere from 1 percent to 20 percent of school-aged children. Many are concerned some children may be receiving drug treatment for the condition when they don't really need it.

In order to accurately determine the incidence of ADHD and which children receive treatment for it, Mayo Clinic investigators looked at all children born in Rochester, Minn., between 1976 and 1982 who remained in the community after age 5. Medical and school records were evaluated for ADHD, then the group was then divided into four sections depending on clinical diagnosis of the condition and supporting documentation from that the condition existed two recognized medical sources.

Children were identified as having a definite diagnosis of ADHD if they were diagnosed by a physician and met criteria for the diagnosis found in one of the two sources. They were identified as having probable ADHD if they had a clinical diagnosis but no supporting documentation, or no clinical diagnosis but documentation from both of the supporting sources.

Those with a questionable diagnosis had no clinical diagnosis but at least one form of supporting documentation, and those with no diagnosis or documentation were considered not to have ADHD.

Results showed a 16 percent incidence of ADHD by age 19 when the first three groups were combined (definite diagnosis, probable diagnosis, and questionable diagnosis). When the researchers looked just at the definite diagnosis group, however, the incidence dropped to 7.4 percent. About 86 percent of those with a definite diagnosis received treatment with medication to control the condition, compared to 40 percent of those with a probable diagnosis, and 6.6 percent of those with a questionable diagnosis.

The researchers conclude those children most likely to have ADHD are most likely the ones to receive treatment.

SOURCE: Archives of Pediatrics & Adolescent Medicine, 2002;156:217-224

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